Most of these have been added and a couple into rotation in GG and DM. The ones that were not loaded were either not immediately available (and I did not look for more than a few seconds) or I was apathetic and didn't grab a couple because meh.

rip

Build a fire for a man, you keep him warm that night.
Set a man on fire, and he'll be warm the rest of his life.

I used to play in a CZ GG server many years ago and it had some good and fun maps. Unfortunately since it was so long ago I've forgotten a lot of the map names but off the top of my head I remember they had these ones which may be worth a try:
aim_crazyjump
fy_simpsons
gg_sys_mini_mario
gg_pacman
gg_33_frisson
gg_33_mario

Maps that are too big and open or don't have much cover aren't too GG friendly since it makes getting a knife kill hard and can potentially lead to long games. So for maps that should be cycled out for those reasons, I think aim_ak-colt would be at the top of the list and fy_hotspot wouldn't be bad to cycle out either.

In general gg_ maps are designed to be GG friendly in most cases so they're worth giving a try for sure. For example, kim knifed me like 5 times on the same map when we played gg_dusted_houses once. >:(